Mechanics of Breathing II Flashcards
How is airflow calculated?
Airflow (V) = Δ Pressure (P) / Resistance (R)
More resistance means what to air flow?
it will be lower
how can resistance in airflow be overcome?
increasing pressure difference between two ends
hagen-poiseuille equation
Resistance (R) α 1/radius4
two types of airflow
laminar and turbulent
what is loss of patency?
closing or obstruction
what is the open structure of airways maintained by?
elastic fibres within the wall of the airway and radial traction
why is airway obstruction more noticeable in expiration?
lung tissue and airways are compressed
what happens when intrapleural pressure becomes positive?
collapsing force will be exerted onto airways
how is spirometry calculated?
FEV1/FVC
how is spirometry measured?
patient produces max forced expiration plotted on a graph
what is FEV1
forced expiratory volume in 1 second
what is FVC
forced vital capacity
obstructive airway diseases
asthma and chronic bronchitis
what will change in the ratio for obstructive diseases
FEV1 decreases and so will the ratio
restrictive lung diseases
pulmonary fibrosis, indicated by reduction in FEV1 and FVC so ratio is normal
what does difference between pressure within alveoli and intrapleural space determine?
level of force acting to expand or compress the lungs
what happens to intrapleural pressure in inspiration?
increasingly negative because lung volume increases due to elastic properties
high lung compliance?
less elastic recoil = less force required to inflate = more volume change per pressure change
low lung compliance?
more elastic recoil = more force required to inflate = less volume change per pressure change
how is compliance calculated?
compliance = Δvolume / Δpressure
low compliance
stiff, pulmonary fibrosis. greater pressure change required to produce same change in volume